Computer-aided solvent screening for biocatalysis

Abstract

A computer-aided solvent screening methodology is described and tested for biocatalytic systems composed of enzyme, essential water and substrates/products dissolved in a solvent medium, without cells. The methodology is computationally simple, using group contribution methods for calculating constrained properties related to chemical reaction equilibrium, substrate and product solubility, water solubility, boiling points, toxicity and others. Two examples are provided, covering the screening of solvents for lipase-catalyzed transesterification of octanol and inulin with vinyl laurate. Esterification of acrylic acid with octanol is also addressed. Solvents are screened and candidates identified, confirming existing experimental results. Although the examples involve lipases, the method is quite general, so there seems to be no preclusion against application to other biocatalysts.

Heterogeneous biocatalytic processes of vegetable oil interesterification to biodiesel

“…Searching for and selecting the optimum composition of the reaction mixture (substrates, co solvent, and solvent) for a particular lipase catalyzed enzymatic reaction is a challenging scientific and practical problem. The authors [25] described an approach for computer simulations (computer aided molecular design) and selecting candidates for the optimum composition of the reaction mixture. The calculations were based on thermodynamic equilib rium constants, substrate conversion, the solubility of the substrates in the reaction medium and in water, and the physicochemical properties (boiling point) and toxicity of the solvents.…”

“…The calculations were based on thermodynamic equilib rium constants, substrate conversion, the solubility of the substrates in the reaction medium and in water, and the physicochemical properties (boiling point) and toxicity of the solvents. The number of options at the input was 10 5 ; at the output, 5-10 promising can didates were found for further scaling [25]. The calcu lated model parameters of the solvents and the experi mental data were compared to determine semiempiri cal correlations [25].…”

“…The number of options at the input was 10 5 ; at the output, 5-10 promising can didates were found for further scaling [25]. The calcu lated model parameters of the solvents and the experi mental data were compared to determine semiempiri cal correlations [25]. iso Octane, acetone, toluene, and hexane were the best solvents for the interesterifi cation of inulin, vinyl laurate, and octanol conducted using lipase B from Candida antarctica; the conversion was 92-100% [25].…”

“…The calcu lated model parameters of the solvents and the experi mental data were compared to determine semiempiri cal correlations [25]. iso Octane, acetone, toluene, and hexane were the best solvents for the interesterifi cation of inulin, vinyl laurate, and octanol conducted using lipase B from Candida antarctica; the conversion was 92-100% [25]. When tert butanol or pyridine were used as the solvents, the rates of conversion were 69 and 57%, respectively.…”

“…The lower alcohols are known to quickly inactivate enzymes, so methanol is added in small portions (stepwise, up to 12 times during a 30 hour reaction cycle) to reduce inactivation [24][25][26]. In [27], it was found that the inactivation of biocatalysts proceeds faster in methanol than in ethanol, and the commer cial Lypozyme ® TL IM biocatalysts inactivate faster than Novozyme ® 435 [27].…”